The present invention relates generally to methods and apparatus for piston assemblies. More particularly, the present invention relates to single piece pistons for use in reciprocating compressors.
In a reciprocating compressor, the piston sealingly engages a cylinder to form a sealed volume, the size of which changes with the position of the piston. As the piston moves in a first direction, the size of the sealed volume increases and fluid is drawn into the cylinder. As the piston moves in the opposite direction, the size of the sealed volume is decreased and the fluid within the cylinder is compressed. The movement of the piston alternates so as to provide a source of pressurized fluid.
The movement of the piston is controlled through to a rod connects the piston to a reciprocating engine or other power source. In most applications, the mass of the piston and rod at least partially limit the maximum speed at which the piston moves. Because the speed of the piston directly controls the performance of the compressor, it is often desirable to minimize the mass of the piston so as to maximize the speed at which the piston can travel.
Many larger diameter piston assemblies include several component pieces that are assembled together and held in place by attachment to the rod. The attachment of the piston to the rod may pre-stress the rod to the extent that the load capability of the rod is reduced. Further, many multiple piece piston assemblies include components constructed from different materials selected so as to reduce the overall weight of the assembly. The multiple materials and multiple components further add to the complexity of the piston and rod assembly.
Thus, there remains a need to develop methods and apparatus for piston assemblies, which overcome some of the foregoing difficulties while providing more advantageous overall results.